1.2 - Memory & Storage Flashcards
What are the two types of primary storage?
- Random Access Memory (RAM)
- Read Only Memory (ROM)
What does Random Access Memory (RAM) do?
Holds open programs and data until the CPU is turned off (it is volatile)
Is RAM volatile or non-volatile?
Volatile
What does Read Only Memory (ROM) do?
Contains the bootstrap loader / Bios / loads the OS from storage into RAM
Is ROM volatile or non-volatile?
Non-volatile
What is secondary storage?
Permanent, non-volatile, long term storage for programs and data
What is virtual memory?
When RAM is full, part of the secondary storage may be used like RAM, storing open programs
What are the three types of secondary storage?
- Magnetic
- Optical
- Solid state
How does magnetic storage work?
A read/write head moves nanometres above the disk platter and uses the magnetic field of the platter to read or edit data
What is an example of a magnetic storage device?
Hard Disk Drive (HDD)
What are the advantages and disadvantages of magnetic storage?
Advantages:
- Large capacity
- Reliable
- Durable
- Portable
- Faster access speed than optical storage
Disadvantages:
- Slower access speed than solid state
How does optical storage work?
Uses a laser to project beams of light onto a spinning disc
What are examples of optical storage devices?
CDs, DVDs and Blu-Ray
What are the advantages and disadvantages of optical storage?
Advantages:
- Portable
- Cheap
Disadvantages:
- Not durable
- Low capacity per disc
- Slowest access speed
How does solid state storage work?
Electronic circuitry
What is are examples of solid state storage device?
Solid State Drives (SSD), USB flash drives and memory cards
What are the advantages and disadvantages of solid state storage?
Advantages:
- Fastest access speed
- Durable
- Portable
- High capacity
Disadvantage
- Most expensive per MB
What is a character set?
A table that assigns each character a unique binary value
How many bits does ASCII have to represent a character?
8 bits per character
How many characters does ASCII have room to represent?
2^8 = 256
What can Unicode do?
Represent thousands of characters
What is image resolution?
Number of pixels
What is colour depth?
Number of bits per pixel used to represent colours
What are examples of metadata?
Height, width, colour depth, file type, geolocation, camera model, date taken, etc.
What is sample rate?
Number of samples per second (Hz)
The number of times per second that sound is captured
What is bit depth?
Number of bits used to represent a sample
What is compression and why is it used?
Reducing file size to take up less storage space and have shorter transmission times and use less bandwidth
What does lossy compression do?
Deletes parts of the file permanently
What can lossy compression be used for?
Images and audio
What does lossless compression do?
Represents the file in a more efficient way
Reduces the size of the file but no data is lost, the file is restored to the original when opened.
What can lossless compression be used for?
Text documents and program files
